Bob Bohl of the Des Moines police said the accident happened Thursday at about 9 p.m. in 22700 block of Marine View Drive.
A 52-year-old woman stepped out into traffic and was struck by a vehicle heading south on Marine View Drive. The victim sustained critical injuries and was transported to Harborview Medical Center, where she died Saturday morning.
Investigators initially had no information about the vehicle that hit the woman since no witnesses remained.
But police later were able to obtain information indicating the hit-and-run vehicle may have been a tan or yellow four-door older model Toyota or similar type car that has fresh front-end damage.
Anyone with information is asked to contact the Des Moines Police Department at (206) 878-3301. The case number for the incident is 12-2566.